Method for determining valid subframe for non-licensed band in wireless communication system, and apparatus using the method

ABSTRACT

A method of deriving channel state information in an unlicensed band, which is performed by a user equipment, includes based on a subframe being in a cell on the unlicensed band and all of orthogonal frequency division multiplexing (OFDM) symbols of the subframe being occupied by a base station, and based on a channel state information-reference signal (CSI-RS) resource being in the subframe, considering the subframe as a valid subframe, deriving the channel state information in the valid subframe, and transmitting the channel state information to the base station.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.15/753,840, filed on Feb. 20, 2018 (now U.S. Pat. No. 10,470,049, issuedon Nov. 5, 2019), which was filed as the National Phase of PCTInternational Application No. PCT/KR2016/009255, filed on Aug. 22, 2016,which claims priority under 35 U.S.C. 119(e) to U.S. ProvisionalApplication No. 62/207,935, filed on Aug. 21, 2015, No. 62/209,317,filed on Aug. 24, 2015 and No. 62/244,695, filed on Oct. 21, 2015, allof these applications are hereby expressly incorporated by referenceinto the present application.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a wireless communication, moreparticularly to a method for determining a valid subframe for anunlicensed band cell in a wireless communication system and an apparatususing this method.

Description of the Related Art

In International Telecommunication Union Radio communication sector(ITU-R), a standardization task for International MobileTelecommunication (IMT)-Advanced, that is, the next-generation mobilecommunication system since the third generation, is in progress.IMT-Advanced sets its goal to support Internet Protocol (IP)-basedmultimedia services at a data transfer rate of 1 Gbps in the stop andslow-speed moving state and of 100 Mbps in the fast-speed moving state.

3^(rd) Generation Partnership Project (3GPP) provides LTE-Advanced(LTE-A) improved from Long Term Evolution (LTE) based on OrthogonalFrequency Division Multiple Access (OFDMA)/Single Carrier-FrequencyDivision Multiple Access (SC-FDMA) transmission schemes as a systemstandard to satisfy the requirements of IMT-Advanced. LTE-Advanced isone of strong candidates for IMT-Advanced.

In the existing LTE-A, up to five carriers (cells) are aggregated toprovide Carrier Aggregation (CA), but, in the future wirelesscommunication system, considered is eCA (enhanced CA) aggregating up to32 carriers. The eCA may also be referred to as a massive CA.

On the other hand, in future radio communication systems, carrieraggregation of cells in the permitted band and cells in the unlicensedband is also considered. The related technology is LAA(Licensed-Assisted Access using LTE). LAA means a technology thatbundles the licensed band and the unlicensed band into one using thecarrier aggregation technique, with the LTE licensed band as an anchor.A terminal always uses the service by accessing the network with theunlicensed band, and a base station may aggregate the licensed band andthe unlicensed band with the carrier aggregation according to thesituation to offload the traffic of the licensed band into theunlicensed band. In this carrier aggregation, the licensed band canbecome a primary cell (PCell) and the unlicensed band can be used as asecondary cell (SCell). The unlicensed band is active only throughcarrier aggregation and may not perform LTE communication independently.

Such a cell in the unlicensed band is not guaranteed to be alwaysavailable to the base station and the terminal. Therefore, it isunreasonable to apply the CSI reporting method defined for the cell ofthe existing licensed band equally to the cells of the unlicensed band.In particular, a CSI reference resource to be measured for CSI reportingis defined only for a valid subframe, and it may be a problem how todetermine the valid subframe in the cell of the unlicensed band.

SUMMARY OF THE INVENTION

The present invention provides a method for determining a valid subframefor an unlicensed band cell in a wireless communication system and anapparatus using the method.

In one aspect, provided is a method for determining a valid subframe foran unlicensed band cell in a wireless communication system. The methodincludes determining whether all of orthogonal frequency divisionmultiplexing (OFDM) symbols of a subframe in the cell are available, anddetermining whether the subframe is a valid subframe based on whether achannel state information-reference signal (CSI-RS) resource exists inthe subframe, when all of the OFDM symbols of the subframe areavailable.

The subframe may be determined as the valid subframe, when the CSI-RSexists resource in the subframe.

The cell in the unlicensed cell may be aggregated in carriers with acell in a license cell.

The cell in the license cell may be used as a primary cell, and the cellin the unlicensed band is used as a secondary cell.

The valid subframe may be a valid downlink subframe or a valid specialsubframe.

A transmission power value or a clear channel assessment (CCA) thresholdmay be informed to a terminal.

The CCA threshold may be a value for determining whether the cell in theunlicensed band is accessible, and if the CCA threshold is high, anaccess probability may be high, and if the CCA threshold is low, theaccess probability may be low.

The transmission power value may be in an inversely proportionalrelationship to the CCA threshold.

In another aspect, provided is a wireless apparatus. The wirelessapparatus includes a radio frequency (RF) unit and a processor coupledto the RF unit. The processor is configured to determine whether all oforthogonal frequency division multiplexing (OFDM) symbols of a subframein an unlicensed cell are available, and determine whether the subframeis a valid subframe based on whether a channel stateinformation-reference signal (CSI-RS) resource exists in the subframe,when all of the OFDM symbols of the subframe are available.

According to the present invention, a valid subframe can be determinedin consideration of the characteristics of an unlicensed band cell.Unnecessary or meaningless measurement in a terminal can be prevented,and thus waste in power can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the structure of a radio frame in 3GPP LTE/LTE-A.

FIG. 2 shows an example of a resource grid for one slot.

FIG. 3 shows the structure of an uplink subframe.

FIG. 4 shows the structure of a downlink subframe.

FIG. 5 illustrates an EPDCCH.

FIG. 6 shows an example of comparing a carrier aggregation system withthe conventional single carrier system.

FIG. 7 illustrates the non-cross carrier scheduling and the crosscarrier scheduling.

FIG. 8 illustrates a CSI transmission subframe and a CSI referenceresource.

FIG. 9 shows an example of a valid subframe related to UCELL (LAA Scell)(which can be used/considered as a CSI reference resource).

FIG. 10 shows an example of a valid subframe related to UCELL (LAASCELL) (which can be used/considered as a CSI reference resource) whenthe transmission mode of a particular terminal is configured(/signalled) to transmission mode 9 or 10.

FIG. 11 illustrates a method for determining a valid subframe (which maybe used/considered as a CSI reference resource) for a unlicensed bandcell (UCELL, LAA Scell) according to an embodiment of the presentinvention.

FIG. 12 is a block diagram illustrating a base station and a terminal.

DETAILED DESCRIPTION OF THE INVENTION

The following technology can be used in a variety of multiple accessschemes, such as Code Division Multiple Access (CDMA), FrequencyDivision Multiple Access (FDMA), Time Division Multiple Access (TDMA),Orthogonal Frequency Division Multiple Access (OFDMA), and SingleCarrier-Frequency Division Multiple Access (SC-FDMA). CDMA can beimplemented using radio technology, such as Universal Terrestrial RadioAccess (UTRA) or CDMA2000. TDMA can be implemented by radio technology,such as Global System for Mobile communications (GSM)/General PacketRadio Service (GPRS)/Enhanced Data Rates for GSM Evolution (EDGE). OFDMAcan be implemented by radio technology, such as IEEE 802.11 (Wi-Fi),IEEE 802.16 (WiMAX), IEEE 802.20, or Evolved UTRA (E-UTRA). IEEE 802.16mis the evolution of IEEE 802.16e, and it provides backward compatibilitywith a system based on IEEE 802.16e. UTRA is part of a Universal MobileTelecommunications System (UMTS). 3rd Generation Partnership Project(3GPP) Long Term Evolution (LTE) is part of an Evolved UMTS (E-UMTS)using Evolved-UMTS Terrestrial Radio Access (E-UTRA). 3GPP LTE adoptsOFDMA in downlink and adopts SC-FDMA in uplink. LTE-Advanced (A) is theevolution of 3GPP LTE. In order to clarify a description, a situation inwhich the present invention is applied to an LTE-A system is assumed,but the technical spirit of the present invention is not limitedthereto.

FIG. 1 shows the structure of a radio frame in 3GPP LTE/LTE-A.

Referring to FIG. 1, the radio frame includes 10 subframes, and each ofthe subframes includes 2 slots. The slots within the radio frame aregiven slot numbers from #0 to #19. The time that is taken for onesubframe to be transmitted is called a Transmission Time Period (TTI).The TTI can be called a scheduling unit for data transmission. Forexample, the length of one radio frame can be 10 ms, the length of onesubframe can be 1 ms, and the length of one slot can be 0.5 ms. Thestructure of the radio frame is only an example. Accordingly, the numberof subframes included in the radio frame or the number of slots includedin the subframe can be changed in various ways.

FIG. 2 shows an example of a resource grid for one slot.

The slot includes a downlink slot and an uplink slot. The downlink slotincludes a plurality of Orthogonal Frequency Division Multiplexing(OFDM) symbols in a time domain. The OFDM symbol indicates a specifictime period, and the OFDM symbol may also be called an SC-FDMA symboldepending on a transmission method. The downlink slot includes an N_(RB)number of Resource Blocks (RBs) in a frequency domain. The RB is aresource allocation unit, and the RB includes one slot in the timedomain and a plurality of contiguous subcarriers in the frequencydomain.

The number of RBs N_(RB) included in the downlink slot depends on adownlink transmission bandwidth configured in a cell. For example, in anLTE system, the number N_(RB) can be any one of 6 to 110. An uplink slotcan have the same structure as the downlink slot.

Each element on the resource grid is called a Resource Element (RE). AnRE on the resource grid can be identified by an index pair (k,l) withina slot. Here, k (k=0, . . . , N_(RB)×12−1) is a subcarrier index withinthe frequency domain, and l (l=0, . . . , 6) is an OFDM symbol indexwithin the time domain.

One RB is illustrated as including 7×12 REs, including 7 OFDM symbols inthe time domain and 12 subcarriers in the frequency domain, but thenumber of OFDM symbols and the number of subcarriers within one RB arenot limited thereto. The number of OFDM symbols and the number ofsubcarriers can be changed in various ways depending on the length of aCP, frequency spacing, etc. For example, in the case of a normal CyclicPrefix (CP), the number of OFDM symbols is 7 and in the case of anextended CP, the number of OFDM symbols is 6. In one OFDM symbol, one of128, 256, 512, 1024, 1536, and 2048 can be selected and used as thenumber of subcarriers.

FIG. 3 shows the structure of an uplink subframe.

The uplink subframe can be divided into a control region and a dataregion in a frequency domain. Physical uplink control channels (PUCCHs)on which uplink control information is transmitted is allocated to thecontrol region. Physical uplink shared channels (PUSCHs) on which dataare transmitted are allocated to the data region. A terminal may send ormay not send a PUCCH and a PUSCH at the same time depending on aconfiguration.

A PUCCH for one terminal is allocated as an RB pair in a subframe. RBsbelonging to the RB pair occupy different subcarriers in a first slotand a second slot. A frequency occupied by RBs that belong to an RB pairallocated to a PUCCH is changed on the basis of a slot boundary. This iscalled that the RB pair allocated to the PUCCH has been frequency-hoppedin the slot boundary. A terminal can obtain a frequency diversity gainby sending uplink control information through different subcarriers overtime.

Uplink control information transmitted on a PUCCH includes ACK/NACK(also indicated as a HARA-ACK), Channel State Information (CSI)indicative of a downlink channel state, a Scheduling Request (SR), thatis, an uplink radio resource allocation request, etc. The CSI includes aPrecoding Matrix Index (PMI) indicative of a precoding matrix, a RankIndicator (RI) indicative of a rank value that is preferred by UE, aChannel Quality Indicator (CQI) indicative of a channel state, etc. ThePMI and RI may be the CSI reported by a terminal to support amulti-input multi-output (MIMO) operation.

A PUSCH is mapped to an uplink shared channel (UL-SCH), that is, atransport channel. Uplink data transmitted on the PUSCH can be atransmission block, that is, a data block for an UL-SCH that istransmitted during a TTI. The transmission block can be userinformation. Alternatively, the uplink data can be multiplexed data. Themultiplexed data can be obtained by multiplexing the transmission blockfor the UL-SCH and control information. For example, control informationmultiplexed with data can include a CQI, a PMI, ACK/NACK, an RI, etc.Alternatively, only the UCI is sent in the PUSCH.

FIG. 4 shows the structure of a downlink subframe.

The downlink subframe includes two slots in a time domain, and each ofthe slots includes 7 OFDM symbols in a normal CP. A maximum of former 3OFDM symbols (i.e., a maximum of 4 OFDM symbols for a 1.4 MHz bandwidth)in the first slot within the downlink subframe corresponds to a controlregion to which control channels are allocated, and the remaining OFDMsymbols correspond to a data region to which Physical Downlink SharedChannels (PDSCHs) are allocated. The PDSCH means a channel on which datais transmitted from a BS or a node to UE.

Control channels transmitted in the control region include a physicalcontrol format indicator channel (PCFICH), a physical hybrid-ARQindicator channel (PHICH), and a physical downlink control channel(PDCCH).

A PCFICH transmitted in the first OFDM symbol of the subframe carries aControl Format Indicator (CFI), that is, information about the number ofOFDM symbols (i.e., the size of the control region) that is used to sendcontrol channels within the subframe. A terminal first receives a CFI ona PCFICH and then decodes a PDCCH. Unlike a PDCCH, a PCFICH does not useblind decoding, and the PCFICH is transmitted through the fixed PCFICHresource of a subframe.

A PHICH carries an acknowledgement (ACK)/not-acknowledgement (NACK)signal for an uplink Hybrid Automatic Repeat request (HARQ). An ACK/NACKsignal for uplink data transmitted by UE is transmitted through a PHICH.

A PDCCH is a control channel on which Downlink Control Information (DCI)is transmitted. The DCI can include the allocation of PDSCH resources(also called downlink grant (DL grant)), the allocation of physicaluplink shared channel (PUSCH) resources (also called an uplink grant (ULgrant)), a set of transmit power control commands for individual UEswithin any terminal group and/or the activation of a Voice over InternetProtocol (VoIP) may be included.

FIG. 5 illustrates an EPDCCH.

Referring to FIG. 5, the EPDCCH may be positioned after the existingcontrol region in time domain. For example, if an existing controlregion is transmitted in the first three OFDM symbols of a subframe, theEPDCCH may be positioned in OFDM symbols positioned after the three OFDMsymbols. In the frequency domain, the existing control area and theEPDCCH may be coincident or may be configured differently. For example,the PDCCH is transmitted in the entire system band, whereas the EPDCCHcan be transmitted only in the same frequency band as the PDSCHtransmitted for a specific terminal. FIG. 5 shows an example in whichthe EPDCCH is transmitted only in some frequency bands of theconventional control region. In the EPDCCH, control information for anadvanced UE can be transmitted. In EPDCCH, a reference signaltransmitted for demodulation of the PDSCH can be transmitted.

<Carrier Aggregation: CA>

Now, a carrier aggregation system will be described.

FIG. 6 shows an example of comparing a carrier aggregation system withthe conventional single carrier system.

Referring to FIG. 6, the single-carrier system supports only one carrierfor a UE in an uplink (UL) and a downlink (DL). Although the carrier mayhave various bandwidths, only one carrier is assigned to the terminal.Meanwhile, in a carrier aggregation system, a plurality of componentcarriers (CCs), i.e., DL CCs A to C and UL CCs A to C may be allocatedto the terminal. The component carrier (CC) means a carrier which isused in the carrier aggregation system, and may be referred to as acarrier. For example, three 20 MHz CCs can be allocated to a terminal toallocate a 60 MHz bandwidth.

The carrier aggregation system can be divided into a contiguous carrieraggregation system in which carriers to be aggregated are contiguous toeach other and a non-contiguous carrier aggregation system in whichcarriers are separated from each other. Hereinafter, when it is simplycalled the carrier aggregation system, it should be interpreted suchthat both cases where component carriers are contiguous CCs andnon-contiguous CCs are included.

A CC which is a target when aggregating one or more CCs can directly usea bandwidth that is used in the legacy system in order to providebackward compatibility with the legacy system. For example, a 3GPP LTEsystem can support a bandwidth of 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz,and 20 MHz, and a 3GPP LTE-A system can configure a wideband of 20 MHzor higher by using only the bandwidth of the 3GPP LTE system.Alternatively, the wideband can be configured by defining a newbandwidth without having to directly use the bandwidth of the legacysystem.

A system band of a wireless communication system is divided into aplurality of carrier frequencies. Herein, the carrier frequency impliesa center frequency of a cell. Hereinafter, the cell may imply a DLfrequency resource and a UL frequency resource. Alternatively, the cellmay also imply a combination of a DL frequency resource and an optionalUL frequency resource. In addition, in general, if carrier aggregation(CA) is not considered, UL and DL frequency resources may always existin pair in one cell.

In order to transmit and receive packet data via a specific cell, theterminal first has to complete a configuration of the specific cell.Herein, the configuration implies a state in which system informationrequired for data transmission and reception for the cell is completelyreceived. For example, the configuration may include an overallprocedure that requires common physical layer parameters necessary fordata transmission and reception, MAC layer parameters, or parametersnecessary for a specific operation in an RRC layer. A cell of whichconfiguration is complete is in a state capable of immediatelytransmitting and receiving a packet upon receiving only informationindicating that packet data can be transmitted.

The cell in a state of completing its configuration can exist in anactivation or deactivation state. Herein, the activation implies thatdata transmission or reception is performed or is in a ready state. Theterminal can monitor or receive a control channel (i.e., PDCCH) and adata channel (i.e., PDSCH) of an activated cell in order to confirm aresource (e.g., frequency, time, etc.) allocated to the terminal.

The deactivation implies that data transmission or reception isimpossible and measurement or transmission/reception of minimuminformation is possible. The UE can receive system information (SI)required to receive a packet from a deactivated cell. On the other hand,in order to confirm the resource (e.g., frequency, time, etc.) allocatedto the UE, the UE does not monitor or receive a control channel (i.e.,PDCCH) and a data channel (i.e., PDSCH) of the deactivated cell.

The cell can be classified into a primary cell, a secondary cell, and aserving cell.

The primary cell implies a cell that operates at a primary frequency,and implies a cell in which the terminal performs an initial connectionestablishment procedure or a connection re-establishment procedure withrespect to a base station or a cell indicated as the primary cell in ahandover procedure.

The secondary cell implies a cell that operates at a secondaryfrequency, and once an RRC connection is established, the secondary cellis used to provide an additional radio resource.

When carrier aggregation is not configured or when the terminal cannotprovide carrier aggregation, the serving cell is configured with theprimary cell. If the carrier aggregation is configured, the term‘serving cell’ indicates a cell configured for the terminal, and canconsist of a plurality of cells. One serving cell may consist of onedownlink component carrier (DL CC) or a pair of {DL CC, uplink (UL) CC}.The plurality of serving cells can be configured with a set consistingof a primary cell and one or a plurality of cells among secondary cells.

A primary component carrier (PCC) means a CC (component carrier)corresponding to the primary cell. The PCC is a CC that establishes aninitial connection (or RRC connection) with the base station amongseveral CCs. The PCC serves for connection (or RRC connection) forsignaling related to a plurality of CCs, and is a special CC thatmanages UE context which is connection information related to the UE. Inaddition, the PCC establishes a connection with the UE, and thus alwaysexists in an activation state when in an RRC connected mode. A DL CCcorresponding to the primary cell is called a downlink primary componentcarrier (DL PCC), and a UL CC corresponding to the primary cell iscalled an uplink primary component carrier (UL PCC).

A secondary component carrier (SCC) implies a CC corresponding to thesecondary cell. That is, the SCC is a CC allocated to the terminal inaddition to the PCC, and the SCC is an extended carrier used by the UEfor additional resource allocation or the like in addition to the PCC,and can operate either in an activation state or a deactivation state.The DL CC corresponding to the secondary cell is called a DL secondaryCC (DL SCC), and a UL CC corresponding to the secondary cell is called aUL secondary CC (UL SCC).

The primary cell and the secondary cell have the following features.

First, the primary cell is used for PUCCH transmission. Second, theprimary cell is always activated, whereas the secondary cell relates toa carrier which is activated/deactivated according to a specificcondition. Third, when the primary cell experiences a radio link failure(RLF), RRC re-connection is triggered, the RRC re-connection is nottriggered. Fourth, the primary cell can change by a handover procedureaccompanied by a random access channel (RACH) procedure or security keymodification. Fifth, non-access stratum (NAS) information is receivedthrough the primary cell. Sixth, the primary cell always composed of apair of a DL PCC and a UL PCC. Seventh, for each terminal, a differentCC can be configured as the primary cell. Eighth, the primary cell canbe replaced only through a handover, cell selection/cell reselectionprocedure. When adding a new secondary cell, RRC signaling can be usedfor transmission of system information of a dedicated secondary cell.

Regarding a CC constructing a serving cell, a DL CC can construct oneserving cell, or the DL CC can be connected to a UL CC to construct oneserving cell. However, the serving cell is not constructed only with oneUL CC.

Activation/deactivation of a CC is equivalent in concept toactivation/deactivation of a serving cell. For example, if it is assumedthat a serving cell 1 consists of a DL CC 1, activation of the servingcell 1 implies activation of the DL CC 1. If it is assumed that aserving cell 2 is configured by connecting a DL CC 2 and a UL CC 2,activation of the serving cell 2 implies activation of the DL CC 2 andthe UL CC 2. In this sense, each CC can correspond to the serving cell.

The number of component carrier waves aggregated between a downlink andan uplink may be configured differently. The case where the number ofdownlink CCs is equal to the number of uplink CCs is referred to as asymmetric aggregation, and the case where the number of downlink CCs isdifferent from the number of uplink CCs is referred to as asymmetricaggregation. Also, the size (i.e. bandwidth) of the CCs may bedifferent. For example, if five CCs are used for a 70 MHz bandconfiguration, then they may be configured such as 5 MHz CC (carrier#0)+20 MHz CC (carrier #1)+20 MHz CC (carrier #2)+20 MHz CC+5 MHz CC(carrier #4).

As described above, the carrier aggregation system can support multiplecomponent carriers (CCs) unlike a single carrier system. That is, thesystem can support a plurality of serving cells.

Such the carrier aggregation system can support a non-cross carrierscheduling and a cross carrier scheduling.

FIG. 7 illustrates the non-cross carrier scheduling and the crosscarrier scheduling.

Non-cross-carrier scheduling may be referred to be as a method of simplyextending and applying a conventional scheduling method in a single cellto a plurality of cells. If there is a PDSCH scheduled by a PDCCH, thePDCCH/PDSCH is transmitted through the same CC, and the PDCCH mayschedule a PUSCH transmitted through a CC basically linked to a specificCC. The non-cross carrier scheduling may be referred to be as a selfscheduling.

Cross-carrier scheduling (CCS) is a scheduling method capable ofperforming the resource assignment of PDSCHs transmitted throughdifferent CCs and/or the resource assignment of PUSCHs transmittedthrough CCs other than CCs basically linked to a specific CC, through aPDCCH transmitted through the specific CC. That is, a PDCCH and a PDSCHmay be transmitted through different DL CCs, and a PUSCH may betransmitted through another UL CC other than an UL CC that is basicallylinked to a DL CC on which a PDCCH including an UL grant has beentransmitted. As described above, in a system supporting cross-carrierscheduling, a carrier indicator informing that a PDSCH/PUSCH providingcontrol information are transmitted through what DL CC/UL CC isnecessary for a PDCCH. A field including such a carrier indicator ishereinafter called a Carrier Indication Field (CIF).

A carrier aggregation (CA) system supporting cross-carrier schedulingmay include the Carrier Indication Field (CIF) in a conventionalDownlink Control Information (DCI) format. In a system supportingcross-carrier scheduling, for example, in an LTE-A system, 3 bits may beextended because a CIF is added to an existing DCI format (i.e., a DCIformat used in LTE), and in the structure of a PDCCH, an existing codingmethod and resource assignment method (i.e., resource mapping based on aCCE) may be reused.

The present invention will now be described.

The present invention proposes a method for efficiently performing ameasurement operation (for example, a CSI measurement operation and/oran RRM measurement operation) for a Licensed-Assisted Access using LTE(LAA) carrier. Herein, for example, how to determine a valid subframerelated to the corresponding measurement operation is also proposed.

Here, for example, the LAA refers to an LTE licensed band as an anchor,and is used for an authorized band (for example, PRIMARY CELL(/CARRIER)) and an unlicensed band (for example, SECONDARYCELL/CARRIER)) is bundled into one using a carrier aggregationtechnique. Herein, for example, allowing the terminal to use (basic)service (/communication) by initially accessing to a network (always) inthe licensed band, the base station can configure (/signal) the licensedband and the unlicensed band with the carrier aggregation technique asneeded (/required). Here, for example, through the corresponding(licensed/unlicensed band) carrier aggregation technique configuration(/signaling), it is possible to offload traffic of the licensed band tothe unlicensed band, and/or increase DATA (RATE/THROUGHPUT) (byadditionally using (radio) resources of the unlicensed band). Here, forexample, when this type of (licensed/unlicensed band) carrieraggregation is configured (/signalled), the licensed band is configured(/signalled) in the primary cell, and the unlicensed band is configured(/signalled) in the secondary cell. Herein, for example, the unlicensedband may be activated as the secondary cell (/carrier) only with thecarrier aggregation technique, and may not be activated for LTEcommunication independently (for example, as the primary cell(/carrier)).

In the present description, the LAA carrier, for example, may be anunlicensed band carrier. Here, for example, signal transmission may beperformed based on LBT (LISTEN BEFORE TALK) operation and/or CS (CARRIERSENSING) operation in the LAA carrier. Here, for example, the (wireless)communication of the LAA carrier is performed in an aperiodic form (forexample, opportunistically performed only when the result of performingthe LBT (/CS) is “IDLE”), and thus channel state information (CSI)generation, and radio resource management (RRM) related measurementoperation is required to be performed efficiently (so that theinformation (/state) at the time of actual (wireless) communication isreflected as much as possible (or accurately)).

For example, for convenience of explanation, hereinafter, a cell (forexample, a secondary cell: SCELL) operating in the LAA carrier (and/orthe unlicensed band) is referred to as a ‘UCELL’ and a cell operating inthe licensed band (for example, a primary cell: PCELL) is referred to as‘LCELL’. Here, for example, the UCELL may be used as the secondary cellaccording to the LAA operation described above, and may also be referredto as a LAA SCELL in this sense. Here, for example, a resource periodwhich is reserved//configured in an aperiodic manner in the UCELL(according to the result of performing LBT (/CS)) is referred to as areserved resource period (RESERVED RESOURCE PERIOD: RRP). Here, forexample, the RRP may be reserved (/configured) in units of sub-frames(/symbols) (preconfigured (/signalled)). Here, for example, if at least(base station) fails to occupy (reserve) a resource (for example, 14OFDM symbols (NORMAL CP) of the minimum unit preconfigured (/signalled)related to one subframe configuration) on the UCELL, then it cannot beconsidered that a valid subframe (e.g., a valid downlink subframe, aneffective special subframe) associated with the RRP and/or measurementoperation is reserved (/configured).

For example, the downlink subframe (DOWNLINK SUBFRAME: DL SF) of the RRPperiod, i.e., the PDSCH related control information channel (or theuplink subframe (UPLINK SUBFRAME: UL SF), of the RRP period), which istransmitted on the subframe specified for the downlink purpose, i.e.,the PUSCH-related control information channel transmitted on thesubframe specified for the uplink purpose) can be configured to betransmitted from the LCELL (e.g., PCELL). That is, it may be ‘CROSSCARRIER SCHEDULING (CCS)’. Also, in one example, the control informationchannel may be transmitted from the same UCELL as the data channel. Thatis, it may be ‘SELF-SCHEDULING (SFS)’.

For example, the RRP period on the UCELL may be a resource that isconfigured to be aperiodic or discontinuous depending on the carriersensing (CS) result. Considering this, the corresponding RRP period canbe (re)defined (or (re)interpreted) in terms of terminal operation andassumptions.

For example, the RRP period in the UCELL may be (re)defined by at leastone of 1) the period in which the terminal performs a (time/frequency)synchronization operation on the UCELL, 2) in a synchronization signal(e.g., PSS, SSS) for this is assumed to be transmitted from the basestation, 3) the period in which the terminal performs a CSI measurementoperation on a UCELL, or 4) in which a reference signal (e.g., CRS orCSI-RS) for this is assumed to be transmitted from the base station, or5) the period in which the terminal performs a DCI detection operationrelated to data transmission (/reception) in the UCELL, and (6) theperiod in which the terminal performs a (temporary or provisional)buffering operation on a signal received in the UCELL.

When a transmitting node (e.g., a base station) simultaneously transmitsa downlink (DL) signal in some (or all) UCELL(s) based carrieraggregation (CA) techniques, the ‘transmission power (TRANSMISSIONPOWER: TXP) sharing operation’ can be performed by at least one of thefollowing options.

1) Option 1: Fixed per carrier and the same maximum power is allocated.

2) Option 2: Fixed per carrier but maximum power is allocateddifferently.

3) Option 3: dynamically allocate the maximum power between(corresponding) carriers (at least) based on the number of carriers thatare transmitted within each downlink transmission burst.

When the TXP value of all of the signals transmitted in the unlicensedband (U-BAND) is fixed, as the bandwidth to which the signal istransmitted increases (or the number of UCELL(s) to which the signal is(simultaneously) transmitted increases), the clear channel assessment(CCA) threshold may decrease. Here, for example, the CCA means, afterperforming a CS (/LBT) operation on a (shared) wireless channel,determining (/deciding) whether the channel is (physically) available(busy or idle). Here, for example, the CCA threshold may be a referencevalue when determining whether access (/availability) to the (shared)wireless channel is possible. Here, for example, if the CCA thresholdvalue is high, the probability of occupying the (shared) wirelesschannel is high, whereas, if the CCA threshold is low, the probabilityof occupying the (shared) wireless channel may be low. Here, forexample, the CCA threshold may be in an inversely proportionalrelationship to the transmit power. That is, a CCA threshold value maybe applied to be low when a specific transmission terminal transmits asignal with a high transmission power in the unlicensed band, whereas aCCA threshold value may be applied to be high when a signal istransmitted with a low transmission power.

For example, if the transmit power (P_(H)) is less than or equal to 23dBm, the CCA threshold value can be calculated as follows.CCA threshold=−73 dBm/MHZ+(23 dBm−P_(H))/(1 MHZ)  [Equation 1]

The following table illustrates the relationship between transmit powerP_(H), transmission band and CCA threshold.

TABLE 1 transmit transmission band power (P_(H)) (number of UCELL) CCAthreshold 23 dBm 20 MHZ (one UCELL) −60 dBm (−73 dBm/MHZ * 20 MHZ) 23dBm 40 MHZ (two UCELLs) −57 dBm (−73 dBm/MHZ * 40 MHZ) 20 dBm 20 MHZ(one UCELL) −57 dBm (−70 dBm/MHZ * 20 MHZ) 20 dBm 40 MHZ (two UCELLs)−54 dBm (−70 dBm/MHz * 40 MHz)

That is, the CCA threshold value can be changed according to thetransmission power value, the bandwidth of the signal transmitted in theunlicensed band (or the number of UCELL(s) in which signals are(simultaneously) transmitted).

The fact that the CCA threshold value is changed, as transmission powervalue and the bandwidth of the signal transmitted in the unlicensed band(or the number of UCELL(s) in which the signals are transmittedsimultaneously) changes, can be interpreted that an external (maximum)interference reception level related to data transmission/reception onthe UCELL(s) is changed

For example, if the CCA threshold value is configured low, the external(maximum) interference reception level may be considered relatively low,whereas if the CCA threshold value is configured high, the external(maximum) interference reception level may be considered relativelyhigh.

For example, the fact that the transmit power value related to datatransmission/reception of a specific UCELL is changed in the time domaincan be interpreted that the external (maximum) interference receptionlevel is changed. In this case, if the transmission power value relatedto the data transmission/reception of the specific UCELL is configuredto be low (i.e., if it is highly probable that other transmittingnode(s) nearby determining that the channel is ‘IDLE’ state), then theexternal (maximum) interference reception level may be consideredrelatively high, whereas if the transmission power value related to thedata transmission/reception of the specific UCELL is configured to behigh (i.e., if it is highly probable that other transmitting node(s)nearby determining that the channel is ‘BUSY’ state), then the external(maximum) interference reception level may be considered relatively low.

Hereinafter, presented is a method for efficiently performing theUCELL(s) related measurement (e.g., INTERFERENCE/DESIGNED SIGNALMEASUREMENT, RRM MEASUREMENT) when the level of external interferencerelated to data transmission/reception on the UCELL is changed.

For example, the external interference reception level related to datatransmission/reception on the UCELL can be changed for various reasons(as described above). For example, the external interference receptionlevel related to data transmission/reception on the UCELL may bechanged, due to at least one of change in the CCA threshold value,change in the number of UCELL(s) in which signals are simultaneouslytransmitted, change in the bandwidth of a signal transmitted in theunlicensed band (U-BAND) change in the transmit power related to datatransmission/reception in the specific UCELL.

In the present invention, at least one of i) VALID CSI(/RRM) REFERENCERESOURCE′, ii)′ VALID CSI (/RRM) MEASUREMENT RESOURCE′, iii)′ VALIDCSI(/RRM) CALCULATION RESOURCE′, iv)′ RESOURCE (e.g. SUBFRAME) in which(VALID) DESIRED REFERENCE SIGNAL′ (/‘IMR’) to be actually used for UCELLCSI(/RRM) information generation (/calculation) exists, related to theUCELL CSI (/RRM) report, may be defined as at least one of (1) adownlink subframe belonging to the UCELL RRP period, (2) a downlinksubframe in which a predefined (or signalled) reference signal (e.g.,CSI-RS (and/or CRS)) is actually transmitted even in the RRP period (orin which the predefined (or signalled) IMR is actually existed in theRRP period), (3) a downlink subframe in which a predefined (orsignalled) reference signal is transmitted, regardless of the RRPperiod, (4) a downlink subframe which is actually scheduled in data(e.g., PDSCH) to the terminal. Hereinafter, a method is described indetail, in which (2) a downlink subframe in which a predefined (orsignalled) reference signal (e.g., CSI-RS (and/or CRS)) is actuallytransmitted even in the RRP period (or in which the predefined (orsignalled) IMR is actually existed in the RRP period), is determined asa valid subframe.

First, a CSI reference resource will be described.

FIG. 8 illustrates a CSI transmission subframe and a CSI referenceresource.

Referring to FIG. 8, when a subframe in which a terminal transmits theCSI is referred to as a subframe n, for example, the CSI referenceresource (related to the transmitted CSI (measurement/calculation)) maybe defined as a subframe n-n_(CQI_ref).

The subframe n-n_(CQI_ref) is defined only in a valid subframe (forexample, a valid downlink subframe, valid special subframe) according toa predefined rule.

Now described is how to determine the valid subframe in the UCELL (whichcan be used/considered as the CSI reference resource).

FIG. 9 shows an example of a valid subframe related to UCELL (LAA Scell)(which can be used/considered as a CSI reference resource).

Referring to FIG. 9, a primary cell (Pcell) of the license band and aUCELL (LAA Scell) of the unlicensed band can be configured (/signalled)by the carrier aggregation technique. Here, for example, the validsubframe of UCELL (which may be used/considered as a CSI referenceresource) may be a subframe in which the base station can occupy or useall OFDM symbols in a subframe. That is, in the UCELL, not all subframescan be valid subframes, but only subframes 101, 102, and 103, in which abase station can occupy or use all the OFDM symbols, can be the validsubframe. That is, if any subframe of the UCELL cannot occupy at leastone OFDM symbol, it is not regarded as the valid subframe (effectivedownlink subframe or effective special subframe).

FIG. 10 shows an example of a valid subframe related to UCELL (LAASCELL) (which can be used/considered as a CSI reference resource) whenthe transmission mode of a particular terminal is configured(/signalled) to transmission mode 9 or 10.

Referring to FIG. 10, the primary cell (Pcell) in the license band andthe UCELL (LAA SCELL) of the unlicensed band can be configured(/signalled) by the carrier aggregation technique. Here, for example,when a transmission mode (related to UCELL (LAA SCELL)) is configured(/signalled) to a transmission mode 9 or 10 to a terminal to which thecorresponding carrier aggregation technique is configured (/signalled),a valid subframe (which may be used/considered as CSI-RS referenceresources) may be further restricted to a subframe in which the CSI-RSresources associated with a CSI process, are configured, among subframesin which a base station may occupy or use all OFDM symbols.

For example, when the subframes 201, 202, and 203 are subframes in whichthe base station can occupy or use all the OFDM symbols in a subframe,only the subframe 202 among these subframes may be a subframe in whichthe CSI-RS resource associated with the CSI process is configured. Inthis case, only the subframe 202 becomes the valid subframe.

The following table illustrates the transmission mode and the PDSCHtransmission scheme for each transmission mode.

TABLE 2 Transmission mode Transmission scheme of PDSCH 1 Single-antennaport, port 0 2 Transmit diversity 3 Transmit diversity if the associatedrank indicator is 1, otherwise large delay CDD 4 Closed-loop spatialmultiplexing 5 Multi-user MIMO 6 Closed-loop spatial multiplexing with asingle transmission layer 7 If the number of PBCH antenna ports is one,Single-antenna port, port 0. Otherwise, Transmit diversity If the UE isconfigured without PMI/RI reporting: if the number of PBCH antenna portsis one, single-antenna port, port 0, otherwise transmit diversity. Ifthe UE is configured with PMI/RI reporting: closed-loop spatialmultiplexing 9 If the UE is configured without PMI/RI reporting: if thenumber of PBCH antenna ports is one, single-antenna port, port 0;otherwise transmit diversity. If the UE is configured with PMI/RIreporting or without PMI reporting: if the number of CSI-RS ports isone, single-antenna port, port 7; otherwise up to 8 layer transmission,ports 7-14) 10 If a CSI process of the UE is configured without PMI/RIreporting: if the number of CSI-RS ports is one, single-antenna port,port7; otherwise transmit diversity. If a CSI process of the UE isconfigured with PMI/RI reporting or without PMI reporting: if the numberof CSI-RS ports is one, single-antenna port, port 7; otherwise up to 8layer transmissions, ports 7-14.

FIG. 11 illustrates a method for determining a valid subframe (which maybe used/considered as a CSI reference resource) for a unlicensed bandcell (UCELL, LAA Scell) according to an embodiment of the presentinvention.

Referring to FIG. 11, the wireless device determines whether all OFDMsymbols of the subframe of the UCELL can be occupied or used (S210).

If all the OFDM symbols of the UCELL subframe can be occupied or used,it is determined whether the CSI-RS resource exists in the subframe forthe terminal configured in the transmission mode 9 or 10 (S220).

If the CSI-RS resource exists in the subframe, the wireless deviceconsiders the subframe as the valid subframe (S230). If it is determinedas ‘NO’ in either of the two determination procedures, the subframe isnot regarded as the valid subframe (S240).

Hereinafter, various examples and specific methods to which the presentinvention is applied will be described.

[Proposal Method #1] If at least one of ‘data transmission (e.g., PDSCH,PDCCH) related transmission power value,’ and ‘reference signal (RS)(e.g., CRS, CSI-RS, DRS) transmission related transmit power value’ on aspecific UCELL, is changed in a time domain, then it is configured suchthat ‘RESTRICTED CSI MEASUREMENT’ operation is performed per a subframeset to which the same range (/category) of transmit power value isapplied, depending on the subframe set (e.g., a predefined or signallednumber (e.g., one) of UCELL RRP periods) to which the same transmitpower value is applied, or a predefined rule (or predefined signalledinformation)

Alternatively, if at least one of ‘data transmission related CCAthreshold value’ and ‘reference signal transmission related CCAthreshold value’ is changed in the time domain on a specific UCELL, itmay be configured such that ‘restricted CSI measurement’ operation isperformed per the subframe set in which a subframe set to which the sameCCA threshold value is applied (e.g., a predefined or signalled numberof (e.g., one) UCELL RRP period) or per the subframe set to which thesame range (/category) of CCA threshold is applied depending on apredefined rule (or signalled information).

The ‘restricted CSI measurement’ operation may be interpreted in arestricted sense as a ‘RESTRICTED INTERFERENCE MEASUREMENT’ operationand/or a ‘RESTRICTED RS MEASUREMENT’ operation.

The ‘transmit power value information per subframe set’ or ‘CCAthreshold value information per subframe set’ can be (dynamically)informed to the terminal by the base station through the predefinedsignaling (e.g., DCI).

The indicator indicating the transmit power value per subframe set orthe CCA threshold value information per subframe set may be implicitlyinterpreted as a kind of ‘RESTRICTED CSI MEASUREMENT SF SET INDICATOR.’

When a ‘restricted CSI measurement’ is performed according to [ProposalMethod #1], if a specific CSI measurement subframe set (CSI measurementsubframe set #A) related aperiodic CSI (A CSI) request message isreceived (or an A-CSI request message is received on a specific CSImeasurement subframe set (CSI measurement subframe set #A)), then for‘the valid CSI reference resource’ (or ‘valid CSI measurement resource’or ‘valid CSI calculation resource’) related to the corresponding A-CSIreporting, only the subframe on the same CSI measurement subframe set #Ais restrictedly considered and thus it may be defined to be determined(/selected) (depending on a method for determining a predefined CSIreference resource).

If the ‘restricted CSI measurement’ is performed according to [proposedmethod #1], then for ‘the valid CSI reference resource’ (or ‘valid CSImeasurement resource’ or ‘valid CSI calculation resource’) of periodicCSI (P-CSI) report related to a particular CSI measurement subframe set(CSI measurement subframe set #A), only the subframe on the same CSImeasurement set #A is restrictedly considered and thus it may be definedto be determined (/selected) (depending on a method for determining apredefined CSI reference resource).

Also, when a mode is configured in which ‘data transmission relatedtransmit power (/CCA threshold value)’ and/or ‘reference signaltransmission related transmit power (CCA threshold value)’ is changed inthe time domain (for example, it is considered that ‘restricted CSImeasurement subframe set’ is configured), ‘it may be configured suchthat ‘CSI request field size’ on DCI format 0/4 (transmitted inUE-SPECIFIC SEARCH SPACE: USS) is increased to ‘2 bits’ (from ‘1 bit’).

When a measurement’ is performed according to [Proposed Method #1], therule may be defined in which the CSI report is performed by the terminaldepending on a signalled (or preconfigured) CSI (e.g., P-CSI) reportconfiguration information (e.g., period (/subframe offset/reporting modeetc.), (per restricted CSI measurement subframe set) per the subframeset to which the same transmit power (/CCA threshold) value is applied(e.g. predefined or signalled number of (e.g. one) UCELL RRP period) (orper the subframe set to which the same range (/category) of transmitpower (/CCA threshold) is applied depending on the predefined rule orthe signalled information).

When a ‘restricted CSI measurement’ is performed according to [ProposedMethod #1], the rule may be defined in which the minimum value (and/orthe maximum value and/or average value) is reported by the terminal (asa representative value), among the CSI (e.g. P-CSI) information (e.g.,CQI/RI/PMI) related to the subframe set to which the same transmit power(/CCA threshold) value is applied (e.g. the predetermined or signallednumber of (e.g. one) UCELL RRP period) (or the subframe set to which thesame range (/category) of transmit power (/CCA threshold) is applieddepending on the predefined rule (or signalled information)). Inaddition/alternatively, the rule may be defined such that predefined orsignalled particular CSI information (e.g., RI (/CQI/PMI is relativelylargest (smallest)) and/or higher (or lower) K (e.g., K=2) (P-)CSI(S)(e.g., may be valid only if the restricted CSI measurement subframe setis equal to or greater than 3), are (simultaneously) reported.

For example, the application of these rules may be interpreted such that‘the restricted CSI measurement’ operation is performed per the subframeset to which the same transmit power (/CCA threshold) value is applied(or the subframe set to which the same range (/category) of transmitpower (/CCA threshold) value is applied depending on the predefined rule(or signalled information)), and a conventional predefined (orsignalled) representative (restrictive CSI subframe set related) (P-)CSIinformation (e.g., which is different from performing independent (P-)CSI report per the restricted CSI measurement subframe set) is reported.

Alternatively, if higher (or lower) K (e.g., K=2) (P-)CSI(S) and/or forwhich the minimum value (and/or maximum value and/or predetermined (orsignalled) particular CSI information (e.g., RI (/CQI/PMI)) isrelatively largest (or smallest) is reported (as the representativevalue), then ‘restricted CSI measurement subframe set index’ (and/or thecorresponding ‘UCELL (physical) ID’) information related to the reported(P-)CSI(S) may be configured to be reported together.

[Proposal Method #2] When the transmit power value (and/or the transmitpower value related to data transmission) related to transmission of areference signal (e.g., CRS, CSI-RS, DRS) is changed in the time domainon a specific UCELL, it may be configured such that ‘restricted RRM(e.g. RSRQ, RSSI, RSRP) measurement’ operation is performed per thesubframe set to which the same transmit power value is applied (e.g.,predefined or signalled number of (e.g. one) UCELL RRP period) (or thesubframe set to which the same range (/category) of transmit power valueis applied depending on the predefined rule (or pre-signalledinformation)).

As another example, when a CCA threshold value related to transmissionof a reference signal (and/or a CCA threshold value related to datatransmission) is changed in a time domain on a specific UCELL, it may beconfigured such that ‘restricted RRM measurement’ operation is performedper the subframe set to which the same CCA threshold value is applied(e.g., predefined or signalled number of (e.g. one) UCELL RRP period)(or the subframe set to which the same range (/category) of CCAthreshold value is applied depending on the predefined rule (orpre-signalled information)).

For example, by the terminal, it may be configured such that allmeasurement information (e.g., RSRQ, RSSI, RSRP) per the ‘restricted RRMmeasurement subframe set’ is reported through a predefined channel, orit may be configured such that the maximum value (and/or minimum value)among measurement information per the ‘restricted RRM measurementsubframe set’ (and/or an average value of measurement information per‘restricted RRM measurement subframe set’).

Herein, for example, when reporting the maximum value (and/or theminimum value), the ‘UCELL (physical) ID’ (and/or the ‘restricted RRMmeasurement subframe set index’) information corresponding to themaximum value (and/or minimum value) may also be configured to reporttogether.

Alternatively, by the terminal, it may be configured such that afrequency with which a RSSI which is equal to or greater than (or isequal to or less than) a certain threshold (e.g., may be configured tothe value such as X % of the average RSSI value) per the ‘restricted RRMmeasurement subframe set,’ is measured, a subframe index is measured inwhich the RSSI is measured, or the like, is reported by the terminal.Alternatively, it may be configured such that an average value of theRSSI measurement value equal to or greater than (or equal to or lessthan) a certain threshold value (e.g., may be configured as the valuesuch as X % of the average RSSI value) is reported, or it may beconfigured such that the RSSI measurement is sorted in the order ofamplitude, and then the value corresponding to higher (or lower) X % oran average value of the measured value belonging to the higher (lower) X% is reported.

In addition, the ‘restricted RRM measurement’ operation may beinterpreted in restricted sense of a ‘restricted RSRQ measurement’operation (and/or a ‘restricted RSSI measurement’ operation and/or a ‘restricted RSRP measurement’ operation).

Also, when a mode is configured in which the ‘data transmission relatedtransmit power (/CCA threshold) value’ and/or ‘reference signaltransmission related transmit power (/CCA threshold) value’ are changedin a time domain (for example, ‘restricted RRM (/CSI) measurementsubframe set’ is considered to be configured), the ‘RSSI measurement’ inone subframe may be configured to be performed based on ‘all OFDMsymbols’ rather than only the OFDM symbols containing CRS port 0.

In the described above [Proposal Method #1] and/or [Proposed Method#2], 1) when the ‘transmit power value information per the subframe(set)’ or ‘the CCA threshold value information per the subframe (set)’related to the UCELL is signalled directly to the terminal, 2) wheninformation on the start/end time of the UCELL RRP period is signalled(directly) to the terminal, 3) when the terminal identify (indirectly)information on the start/end time of the UCELL RRP period, then it canbe valid for at least one of them.

In the proposed method, when the same or a certain value (or the samerange (/category) of ‘UCELL data transmission related transmit power(/CCA threshold)’ and/or ‘UCELL reference signal transmission relatedtransmit power (/CCA threshold)’ is guaranteed to be predefined ormaintained at least during the signalled certain period, (and/or theinformation on the start/end time of the UCELL RRP period is signalled(directly) to the terminal, and/or the terminal can identify (directly)the information on the start/end time of the UCELL RRP period),presented is a method for performing efficiently UCELL(s) relatedmeasurement (e.g., interference/corresponding signal measurement, RRMmeasurement).

For example, the period (referred to as the ‘EQ_INTERVEL’) in which thesame or a certain value (or the same range (/category) of ‘UCELL datatransmission related transmit power (/CCA threshold)’ and/or ‘UCELLreference signal transmission related transmit power (/CCA threshold)’is maintained, may be also specified as ‘the predefined or signallednumber of (e.g. one) UCELL RRP period.’

[Proposal Method #3] The ‘valid CSI reference resource’ (or ‘valid CSImeasurement resource’ or ‘valid CSI calculation resource) related to theUCELL CSI report (e.g., P-CSI, A-CSI) in a specific time (subframe #N)may be specified as a specific resource (subframe #K) on theEQ_INTERVEL. In this case, ‘interference measurement’ and/or ‘desiredreference signal (e.g., CRS, CSI-RS) measurement’ related to thecorresponding CSI information generation (/calculation) may beconfigured to use the ‘valid CSI reference resource’ (an ‘interferencemeasurement resource (IMR)’ belonging to ‘the period up to the ‘validCSI reference resource’ (subframe #K)) and/or the ‘desired referencesignal’ (and/or ‘predefined (or signalled) (OFDM) symbol in which areference signal of specific port index is included, derived from amethod for determining the CSI reference resource predefined from thefirst subframe on the EQ_INTERVEL.

As a specific example, if the EQ_INTERVEL is configured to a predefinedor signalled number of (e.g., one) UCELL RRP periods, and if the ‘validCSI reference resource’ related to the UCELL CSI report to be performedon the (LCELL) subframe #6′ is the subframe #5 (or the subframe #2) inthe ‘UCELL RRP period (e.g., RRP composed of ‘subframe #0˜subframe #9),then the terminal performs ‘interference measurement’ and/or ‘desiredreference signal measurement’ related to the corresponding CSIinformation generation (/calculation), by using the ‘desired referencesignal’ (and/or an (OFDM) symbol in which the predetermined (orsignalled) reference signal of specific port index is included) and/orthe ‘IMR’ belonging to the period from the’ UCELL RRP subframe #0′ tothe ‘ UCELL RRP subframe #5’ (or the subframe #2).

As another example, if the ‘valid CSI reference resource’ (or the ‘validCSI measurement resource’ or the ‘valid CSI calculation resource’)related to the UCELL CSI report at the specific time (subframe #N) isspecified as the closest EQ_INTERVEL (prior to and including the time ofthe subframe #(N−4)) or the specific resource (subframe #K) on adifferent EQ_INTERVEL other than the EQ_INTERVEL in the predefined (orsignalled) ‘time window (/duration), then it may be configured such thatthe ‘interference measurement’ and ‘desired reference signalmeasurement’ related to the corresponding CSI information generation(/calculation) is performed as ‘ONE-SHOT resource based measurement’ (orit may be configured such that the corresponding CSI information reportoperation is omitted or the corresponding CSI information report isperformed as a predetermined specific value (e.g., CQI of ‘OOR’, RI of‘1’).

As another example, when the above [Proposed Method #3] is applied, the‘INTERFERENCE AVERAGING’ (and/or ‘averaging of the desired referencesignal’ and/or ‘RRM (e.g., RSRQ, RSSI, RSRP)) operation can beconfigured to (‘reset or initialize’ in units of a predefined (orsignalled) number of (e.g., one) EQ_INTERVEL).

[Proposed Method #4] The UCELL RRM report (e.g., RSRQ, RSSI, RSRP)related information generation (/calculation) of the specific time(subframe #N) may be configured to use the closest EQ_INTERVEL (prior toand including the time of the subframe #(N−4)) or the ‘desired referencesignal (and/or the OFDM symbol in which the predefined (or signalled)reference signal of specific port index is included) and/or the ‘IMR’belonging to the ‘EQ_INTERVEL in the predefined (or signalled) ‘timewindow (/duration).’’

If the [proposed method #4] is applied, then the ‘RRM (e.g., RSRQ, RSSI,RSRP) averaging’ (and/or the ‘interference averaging’ (and/or ‘(desired)reference signal averaging’)) operation may be configured to be reset orinitialized in units of (a predefined (or signalled) number of (e.g.,one)) EQ_INTERVEL.

It is obvious that examples of the proposed scheme described above canalso be included as one of the implementation methods of the presentinvention, and thus can be regarded as a kind of proposed schemes. Inaddition, the proposed schemes described above may be implementedindependently, but they may be implemented by combining (or merging)some of the proposed schemes. For example, the (some or all) proposedschemes of the present invention may be applied not only to the casewhere the unlicensed band is activated (as the secondary cell(/carrier)) only through the carrier aggregation, but also to the casewhere it is activated independently for an LTE communication (e.g., asthe primary cell (/carrier)). For example, the (some or all) proposedschemes of the present invention may be applied only in a limited(preconfigured (/signalled)) transmission mode.

FIG. 12 is a block diagram illustrating a base station and a terminal.

A BS 100 includes a processor 110, a memory 120, and an RF unit 130. Theprocessor 110 implements a proposed function, process, and/or method.The memory 120 is connected to the processor 110 and stores varioustypes of information for operating the processor 110. The RF unit 130 isconnected to the processor 110 and transmits and/or receives a radiosignal.

A UE 200 includes a processor 210, a memory 220, and an RF unit 230. Theprocessor 210 implements a proposed function, process, and/or method.The memory 220 is connected to the processor 210 and stores varioustypes of information for operating the processor 210. The RF unit 230 isconnected to the processor 210 and transmits and/or receives a radiosignal.

The processors 110 and 210 may include an ASIC (Application-SpecificIntegrated Circuit), a chip-set, a logical circuit, a data processor,and/or a converter for converting a baseband signal and a radio signalfrom each other. The memories 120 and 220 may include a ROM (Read-OnlyMemory), a RAM (Random Access Memory), a flash memory, a memory card, astorage medium, and/or any other storage devices. The RF units 130 and230 may include one or more antennas for transmitting and/or receiving aradio signal. When the embodiments are implemented by software, theforegoing techniques may be implemented by modules (processes,functions, or the like) performing the foregoing functions. The modulesmay be stored in the memories 120 and 220 and executed by the processors110 and 210, respectively. The memories 120 and 220 may be providedwithin or outside the processors 110 and 210 and may be connected to theprocessors 110 and 210 through a well-known unit, respectively.

What is claimed is:
 1. A method of deriving channel state information inan unlicensed band, the method performed by a user equipment andcomprising: based on a subframe being in a cell on the unlicensed bandand all of orthogonal frequency division multiplexing (OFDM) symbols ofthe subframe being occupied by a base station, and based on a channelstate information-reference signal (CSI-RS) resource being in thesubframe, considering the subframe as a valid subframe; deriving thechannel state information in the valid subframe; and transmitting thechannel state information to the base station.
 2. The method of claim 1,wherein the cell on the unlicensed band is aggregated with a cell on alicensed band.
 3. The method of claim 2, wherein the cell on thelicensed band is used as a primary cell, and the cell on the unlicensedband is used as a secondary cell.
 4. The method of claim 1, wherein thevalid subframe is a valid downlink subframe or a valid special subframe.5. The method of claim 1, wherein a transmission power value or a clearchannel assessment (CCA) threshold is informed to the user equipment. 6.The method of claim 5, wherein the CCA threshold is a value fordetermining whether the cell on the unlicensed band is accessible, andif the CCA threshold is higher than a threshold, an access probabilityis considered to be high, and if the CCA threshold is lower than thethreshold, the access probability is considered to be low.
 7. The methodof claim 5, wherein the transmission power value is in an inverselyproportional relationship to the CCA threshold.
 8. A user equipment(UE), comprising: a transceiver; and a processor coupled to thetransceiver, wherein the processor is configured to: based on a subframebeing in a cell on an unlicensed band and all of orthogonal frequencydivision multiplexing (OFDM) symbols of the subframe being occupied by abase station, and based on a channel state information-reference signal(CSI-RS) resource being in the subframe, consider the subframe as avalid subframe, derive channel state information in the valid subframe,and transmit the channel state information to the base station.
 9. TheUE of claim 8, wherein the cell on the unlicensed band is aggregatedwith a cell on a licensed band.
 10. The UE of claim 9, wherein the cellon the licensed band is used as a primary cell, and the cell on theunlicensed band is used as a secondary cell.
 11. The UE of claim 8,wherein the valid subframe is a valid downlink subframe or a validspecial subframe.
 12. The UE of claim 8, wherein a transmission powervalue or a clear channel assessment (CCA) threshold is informed to theUE.
 13. The UE of claim 12, wherein the CCA threshold is a value fordetermining whether the cell on the unlicensed band is accessible, andif the CCA threshold is higher than a threshold, an access probabilityis considered to be high, and if the CCA threshold is lower than thethreshold, the access probability is considered to be low.
 14. The UE ofclaim 13, wherein the transmission power value is in an inverselyproportional relationship to the CCA threshold.
 15. A processor for awireless communication device in a wireless communication system,wherein the processor is configured to control the wirelesscommunication device to: based on a subframe being in a cell on anunlicensed band and all of orthogonal frequency division multiplexing(OFDM) symbols of the subframe being occupied by a base station, andbased on a channel state information-reference signal (CSI-RS) resourcebeing in the subframe, consider the subframe as a valid subframe, derivechannel state information in the valid subframe, and transmit thechannel state information to the base station.